Field
The present disclosure relates generally to systems for creating a durable seal between adjacent horizontal panels, including those which may be subject to temperature expansion and contraction or mechanical shear. More particularly, the present disclosure is directed to an expansion joint design for use in surfaces exposed to foot or vehicular traffic.
Description of the Related Art
Construction panels come in many different sizes and shapes and may be used for various purposes, including roadways, sideways, and pre-cast structures, particularly buildings. Historically, these have been formed in place. Use of precast concrete panels for floors, however, has become more prevalent. Whether formed in place or by use of precast panels, designs generally require forming a lateral gap or joint between adjacent panels to allow for independent movement, such in response to ambient temperature variations within standard operating ranges, building settling or shrinkage and seismic activity. Moreover, these joints are subject to damage over time. Most damage is from vandalism, wear, environmental factors and when the joint movement is greater, the seal may become inflexible, fragile or experience cohesive and/or adhesive failure. As a result, “long lasting” in the industry refers to a joint likely to be usable for a period greater than the typical lifespan of five (5) years. Various seals have been created in the field. Moreover, where in a horizontal surface exposed to wear, such as a roadway or walkway, it is often desirable to ensure that contaminants are retarded from contacting the seal and that the joint does not present a tripping hazard, whether as a result of a joint seal system which extends above the adjacent substrates or as a result of positioning the joint seal system below the surface of the substrates. This may be particularly difficult to address as the size of the expansion joint increases.
Various seal systems and configurations have been developed for imposition between these panels to provide seals or expansion joints to provide one or more of fire protection, waterproofing, sound and air insulation. This typically is accomplished with a seal created by imposition of multiple constituents in the joint, such as silicone application, backer bars, and compressible foams.
Expansion joint seal system designs for situations requiring the support of transfer loads have often required the use of rigid extruded rubber or polymer glands. These systems lack the resiliency and seismic movement required in expansion joints. These systems have been further limited in functioning as a fire resistant barrier, which is often a desired function.
Other systems have incorporated cover plates that span the joint itself, often anchored to the concrete or attached to the expansion joint material and which are expensive to supply and install. These systems sometimes require potentially undesirable mechanical attachment, which requires drilling into the deck or joint substrate. Cover plate systems that are not mechanically attached rely on support or attachment to the expansion joint, thereby subjecting the expansion joint seal system to continuous compression, expansion and tension on the bond line when force is applied to the cover plate, which shortens the life of the joint seal system. Some of these systems use foam to provide sealing. But these foam systems can take on a compression set when the joint seal system is repeatedly exposed to lateral forces from a single direction, such as a roadway. This becomes more pronounced as these foam systems utilize a single or continuous spine along the length of the expansion joint seal system—which propagates any deflection along the length. The problems and limitations of the current foam sealing cover plate systems that rely on a continuous spline are well known in the art.
These cover plate systems are designed to address lateral movement—the expansion and compression of adjacent panels. Unfortunately, these do no properly address vertical shifts—where the substrates become misaligned when the end of one shifts vertically relative to the other. In such situations, the components attached to the cover plate are likewise rotated in space causing a pedestrian or vehicular hazard. The current systems do not adequately address the differences in the coefficient of linear expansion between the cover plate and the substrate or allow for curved joint designs. The inability of the current art to compensate for the lateral or thermal movement of the cover plate results in failure of attachment to the cover plate or additional pressure being imposed on one half of the expansion joint system and potentially pulling the expansion joint system away from the lower substrate.